1. Field of the Invention
The invention relates to guide wires and catheters for crossing, opening and/or widening a channel through a totally or partially occluded biological vessel, such as a blood vessel.
2. Description of the Related Art
There are a number of disease conditions involving stenosis, which is the narrowing or obstruction of the interior passage, or lumen, of arteries. These obstructions, generally known as occlusions, are found in patients suffering from atherosclerosis, a condition characterized by an accumulation of fibrous, fatty or calcified tissue in the arteries. As these occlusions can partially or totally block the arterial flow, they can be potentially life threatening. Occlusions may be partial or total, may be soft and pliable or hard and calcified, and may be found at a great variety of sites in the arterial system, including the aorta, the coronary and carotid arteries, and peripheral arteries.
Although the majority of interventional procedures such as balloon angioplasty, atherectomy, and the like bring some degree of relief to the patient and improvement in the blood flow, total or near total occlusions are difficult to treat, as the interventional tool, such as the angioplasty balloon or the atherectomy catheter, often cannot reach and cross the occlusion site to carry out their intended functions. This is generally referred to as an inability to cross, and is the major cause of failure of such procedures.
A number of different instruments have been proposed to open or to cross a totally or partially blocked blood vessel. One such instrument is disclosed in U.S. Pat. No. 5,116,350 to Stevens. Stevens describes a catheter whose distal blunt tip moves back and forth in a ramming motion or whose cutting/abrading distal tip moves back and forth about an axis. Osypka, in U.S. Pat. No. 5,234,451 discloses an apparatus for eliminating occlusions and stenoses in body cavities. The device of Osypka includes a combination of anvil and reciprocating internal hammer to ram the device through occlusions. The hammer repeatedly strikes the anvil to drive the device further within the cavity. Uflacker et al., in U.S. Pat. No. 5,243,997 propose a device to vibrate a guidewire. The vibration induced thereon is asserted to facilitate the pushing of the guidewire past the obstruction. Solar, in U.S. Pat. No. 5,549,119 discloses a vibrating tip catheter, the vibration being asserted to enhance the catheter's ability to cross tight lesions and stenoses.
These devices, however, suffer from a number of disadvantages. It is believed that the sharp back and forth ramming motions of some of these devices may possibly damage the vessel lining and lead to unwanted scar tissue. On the other hand, the vibrating guide wires and tips are not believed wholly effective in crossing total occlusions without damaging the vessel walls. Moreover, it is not believed that these devices possess the ability to sufficiently enlarge an existing channel to allow other, larger, or more aggressive interventional tools to follow and to position themselves across the occlusion.
What is needed, therefore, are improved guide wires and catheters that are able to successfully navigate tortuous regions of a patient's vasculature and to create or enlarge a channel past an occlusion to allow other interventional tools to successfully perform their intended therapeutic functions. What is also needed are such guide wires and catheters that are effective in opening or enlarging channels past an occlusion, while not damaging the vessel walls.